mojo: Fix java generator

mojo/tools/generate_java_callback_interfaces.py

 """Generate the org.chromium.mojo.bindings.Callbacks interface"""
 
 import argparse
 import sys
 
 CALLBACK_TEMPLATE = ("""
     /**
-      * A generic %d-argument callback.
-      *
-      * %s
-      */
+     * A generic %d-argument callback.
+     *
+     * %s
+     */
     interface Callback%d<%s> {
         /**
-          * Call the callback.
-          */
+         * Call the callback.
+         */
         public void call(%s);
     }
 """)
 
 INTERFACE_TEMPLATE = (
 """// Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file was generated using
 //     mojo/tools/generate_java_callback_interfaces.py
 
 package org.chromium.mojo.bindings;
 
 /**
  * Contains a generic interface for callbacks.
  */
 public interface Callbacks {
+
+    /**
+     * A generic callback.
+     */
+    interface Callback0 {
+        /**
+         * Call the callback.
+         */
+        public void call();
+    }
 %s
 }""")
 
 def GenerateCallback(nb_args):
   params = '\n      * '.join(
       ['@param <T%d> the type of argument %d.' % (i+1, i+1)
        for i in xrange(nb_args)])
   template_parameters = ', '.join(['T%d' % (i+1) for i in xrange(nb_args)])
   callback_parameters = ', '.join(['T%d arg%d' % ((i+1), (i+1))
                                    for i in xrange(nb_args)])
   return CALLBACK_TEMPLATE % (nb_args, params, nb_args, template_parameters,
                               callback_parameters)
 
 def main():
   parser = argparse.ArgumentParser(
       description="Generate org.chromium.mojo.bindings.Callbacks")
   parser.add_argument("max_args", nargs=1, type=int,
       help="maximal number of arguments to generate callbacks for")
   args = parser.parse_args()
   max_args = args.max_args[0]
   print INTERFACE_TEMPLATE % ''.join([GenerateCallback(i+1)
                                       for i in xrange(max_args)])
   return 0
 
 if __name__ == "__main__":
   sys.exit(main())